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PGA308: What Reg Set means in Multi-Cal PGA308 Sensor Report ?

Nicky Lim
Genius 3195 points
Part Number: PGA308


Hello,

Customer made Pressure sensor by using PGA308, but some parts have a malfunction.

At that time, there are differents of Reg Set value in Multi-Cal Sensor report as below.

Customer wants to know why Reg Set value is different & meaning of each reg.

Could you let me know the meaning of each reg value ASAP? Because customer line stop due to this issue.

Sensor Report (Malfunction @ 13K) Sensor Report (OK)
General Info General Info
Sensor Pass/Fail = Pass Sensor Pass/Fail = Pass
Serial Numberl = 148 Serial Numberl = 1967
Sensor Channel = 11 Sensor Channel = 0
Date of calibration = 2017-02-24 오전 9:33 Date of calibration = 2017-03-24 오전 8:29
Sensor Output Min = 1.180186E-3 Sensor Output Min = 1.196256E-3
Sensor Output Max = 15.424302E-3 Sensor Output Max = 15.599907E-3
Module Output Min = 576.252300E-3 Module Output Min = 577.727300E-3
Module Output Min = 576.252300E-3 Module Output Min = 577.727300E-3
Module Error Min = -0.043% Module Error Min = -0.008%
Module Output Max = 4.500736E+0 Module Output Max = 4.500061E+0
Module Error Max = 0.018% Module Error Max = 0.003%
Reg Set Reg Set
Reg 0=23.802000E+3 Reg 0=23.781000E+3
Reg 1=34.913000E+3 Reg 1=34.151000E+3
Reg 2=2.177000E+3 Reg 2=2.177000E+3
Reg 3=0.000000E+0 Reg 3=0.000000E+0
Reg 4=0.000000E+0 Reg 4=32.768000E+3
Reg 5=4.643000E+3 Reg 5=38.193000E+3
Reg 6=4.643000E+3 Reg 6=38.193000E+3
Reg 7=256.000000E+0 Reg 7=257.000000E+0
Reg 8=0.000000E+0 Reg 8=0.000000E+0
Reg 9=0.000000E+0 Reg 9=0.000000E+0
Gain and Offset Gain and Offset
Vs = 5.000000E+0 Vs = 5.000000E+0
Vref = 5.000000E+0 Vref = 5.000000E+0
Front Gain = 200.000000E+0 Front Gain = 200.000000E+0
Output Gain = 2.000000E+0 Output Gain = 2.000000E+0
Coarse Off = -2.501563E-3 Coarse Off = -2.501563E-3
Gain Dac = 688.486700E-3 Gain Dac = 680.735235E-3
Zero Dac = 684.023804E-3 Zero Dac = 685.626001E-3

Regards,

Nicky

  • 0
    TI__Mastermind 27715 points

    Hello Nicky,

    The register values between different modules are different because the registers contain gain and offset calibration parameters that are unique for every module. Since each PGA308 has its own internal analog characteristics and sees a different sensor as input, it will need different gain and offset scaling to reach the desired output.

    Below is an explanation of each register. All of this information is available in Section 7 of the PGA308 User's Guide.

    • Reg 0 = Zero DAC - fine offset adjust
    • Reg 1 = Gain DAC - fine gain adjust
    • Reg 2 = CFG0 - configuration register 0, controlling output amplifier gain, front-end PGA gain, coarse offset adjust on front-end PGA
    • Reg 3 = CFG1 - configuration register 1, controlling fault monitor, over/underscale, fault comparator, thresholds and compensation
    • Reg 4 = CFG2 - configuration register 2, controlling one-wire disable, shutdown, clamp, front-end PGA offset reference range
    • Reg 5 = CHKS - checksum for Zero DAC, Gain DAC, CFG0, CFG1, and CFG2 registers
    • Reg 6 = CHSR - checksum read for internally calculated checksum
    • Reg 7 = SFTC - software control for software lock mode, one-wire delay select, OTP bank select for software lock mode
    • Reg 8 = OENC - output countrol control for when 1W is connected to Vout in 3-wire modules
    • Reg 9 = ALRM - fault monitor comparator output register

    There is too much data in all the registers to analyze for you bit-by-bit. However, you should expect Register 0 (Zero DAC) and Register 1 (Gain DAC) to be different for different modules. Register 2 (CFG0) may or may not be different depending on the variation in the input source. 

    You should expect all the registers related to device configuration to be the same - Registers 3, 4, 7, 8, and 9. Registers 4 and 7 are different, so the problem is likely there, especially Register 4. Have the customer investigate the data written to Register 4 to make sure there aren't problems in the configuration of the failed device.

    Best regards,

    Ian Williams
    Applications Engineer - Precision Amplifiers